At the Office of Management and Budget, the executive department charged with managing the sequestration cuts, a total of 480 employees begin furloughs this week. Only a handful of political appointees are exempted. Roughly eight in 10 of the OMB’s staffers are on unpaid furlough today — and will be every other week until October. The rest will be at home without pay next Monday, an alternating schedule that will continue through the end of the fiscal year Sept. 30.

After seven weeks of worries and doubts, the mandatory budget cuts are starting to be felt across the nation. Flight delays and airport security wait times are up, EPA inspections are being deferred, and even those responsible for setting furlough policy at OMB are themselves being furloughed.

The Federal Aviation Administration plan to scale back the hours of all of its 47,000 employees — including 15,000 flight controllers — kicked in on Sunday, requiring an unpaid day off every two weeks. “Yesterday there were approximately 400 delays in the system attributable to staffing reductions resulting from the furlough,” an FAA spokesperson said in a statement to TIME. The Department of Defense’s more than 700,000 civilian employees face as many as 14 furlough days beginning in May.

Employees are prohibited from working during a furlough day even if they want to, and are barred from checking their email for the entire 24-hour period of the furlough day, as well as the preceding Sunday and following Saturday — because then they would need to be paid.

The cuts follow dire warnings from the White House in February about the mandatory sequestration cuts, which hit nearly all federal programs and offices across the board. But the administration failed to avert them as Republicans stood firm against raising revenue to achieve the required deficit reduction under the 2011 Budget Control Act, and Obama was accused of crying wolf by Republicans as the March 1 deadline came and went without much of a hiccup.

But the effects of the cuts are now becoming clear, especially in the nation’s air transit system.

On Monday morning, Delta Airlines issued an advisory to travelers to expect furlough-driven delays or cancellations in some of the biggest and busiest airports: New York, Philadelphia, Chicago, San Francisco, Los Angeles, San Diego, and Fort Lauderdale. The airline encouraged customers to contact their members of Congress to urge a change.

The FAA has postponed the closings of smaller control towers until June from earlier this month, but is experiencing traffic-jams in crowded airspace.

One symptom of the delays: the Associated Press first reported Monday that the 8 a.m. US Airways shuttle to New York from Washington arrived two-hours late — and after the 8 a.m. Acela express train.

Republicans have responded to the flight delays by blasting the Obama administration for furloughing flight controllers, saying the FAA can cut elsewhere — a position argued by Airlines For America, the industry trade group.

“The FAA can make other cost cuts, and deem air traffic controllers ‘essential employees,’” the organization said in a statement on its website geared toward delayed travelers, dontgroundamerica.com.

“The FAA’s management of sequestration is quickly going from bad to worse,” said House Committee on Transportation and Infrastructure Chairman Bill Shuster in a statement, which was tweeted out by Speaker of the House John Boehner with the hashtag “#ObamaFlightDelays.” “Given that the FAA’s budget increased more than 100 percent over the last 15 years, finding five percent in savings shouldn’t need to significantly impact our nation’s aviation operations. Businesses and families across the country face these issues in their budgets every day without massive impacts. We know that the FAA has the flexibility to reduce costs elsewhere, such as contracts, travel, supplies, and consultants, or to apply furloughs in a manner that better protects the most critical air traffic control facilities. Yet rather than take this approach, the Administration has made choices that appear designed to have the greatest possible impact on the traveling public.”

But administration officials maintain they have no flexibility with where they can cut. Press Secretary Jay Carney said at the daily press briefing today that sequestration requires the administration to implement cuts across the board and prohibits agencies from shifting money around to keep vital staff on duty.

Updated at 2:07 p.m. to include FAA statement. The full statement is below:

As a result of employee furloughs due to sequestration, the FAA is implementing traffic management initiatives at airports and facilities around the country. Travelers can expect to see a wide range of delays that will change throughout the day depending on staffing and weather related issues. For example, the FAA is experiencing staffing challenges at New York Center and TRACON, Dallas-Fort Worth Center, Jacksonville Center and Los Angeles Center. Controllers will space planes farther apart so they can manage traffic with current staff, which will lead to delays at airports including New York’s La Guardia Airport. The FAA is working with the airlines throughout the day to try and minimize delays for travelers. We encourage all travelers to check their flight status and also to visit fly.faa.gov for the latest airport delay information.

Yesterday there were approximately 400 delays in the system attributable to staffing reductions resulting from the furlough.